Motorized wheelchair

ABSTRACT

A motorized wheelchair comprising a pair of removable armrests and a backrest that will pivot forwardly from an upright position into one in which it flattens against the seat to overlie the same and minimize the vertical clearance space required by the wheelchair when it is loaded into a vehicle or other restricted space. Motors and batteries for propelling the wheelchair are positioned below the elevation of the seat and are completely functional both when the armrests and the backrest are in their upright positions of use, and when the armrests are removed and the backrest is folded flat. A motor and brake control mechanism is mounted on an armrest along one side thereof, and the armrest can be selectively positioned with the control mechanism extending over the seat for convenient use by an occupant thereof or with the control mechanism extending outwardly from the armrest so as to clear the seat for ready ingress and egress.

United States Patent Chisholm Apr. 30, 1974 MOTORIZED WHEELCHAIR Primary ExaminerDavid Schonbcrg Assistant ExaminerLeslie J. Paperner [76] Inventor S2623" Attorney, Agent, or FirmJoseph B. Gardner, Esq.

[22] Filed: Dec. 15, 1971 I 21 Appl. No.2 208,290 [57] ABSTRACT A motorized wheelchair comprising a pair of remov- 52 US. 01 180/65, 180/010. 3, 297/010. 4 able armrests and a baekrest that will Pivet forwardly 51 1111.01 A6lg 5/04 heme" upright Peehien one in whieh it flattens [58] Field 6: Search 180/65, 010. 3; 297/378, against the Seat to overlie the Same and minimize h 297/379, 416, 417, DIG. 4 vertical clearance space required by the wheelchair when it is loaded into a vehicle or other restricted [56] References Cited space. Motors and batteries for propelling the.wheel- UNITED STATES PATENTS chair are positioned below the elevatlon of the seat and are completely functional both when the armrests g and the backrest are in their upright positions of use, 2586273 2/1952 Steven 3 and when the armrests are removed and the backrest 3:584:890 6/1971 Presty :2: 297 010: 4 folded A motor and brake control mechanism is 2,482,203 9/1949 Peterson et a1... 180/010. 3 mounted on an armrest along one e thereof, and 3,111,181 11/1963 Yatich 180/615 the armrest can be Selectively Positioned with the 2,713,891 v 7/1955 Linquist.... 297/010. 4 rol h ni m x n ing ver he seat for convenient 3,213,957 10/1965 Wrigley..... 297/378 X use by an occupant thereof or with the control -mecha- 3,244,453 4/1966 Fox 297/416 nism extending outwardly from the armrest so as to clear the seat for ready ingress and egress.

4 Claims, 2 Drawing Figures PATENTEBIPR 30 m4 FIG; I

PATENTEB APR 3 0 i974 SHEEI 2 OF 2 FIG. 2

MOTORIZED WHEELCHAIR BACKGROUND OF THE INVENTION This invention relates to motorized wheelchairs and, more particularly, to a wheelchair that may be reduced to somewhat compact dimensions to minimize the storage space required therefor and especially storage space within a vehicle in which the wheelchair may be transported.

Wheelchairs are generally used within certain limited areas such as the home, along corridors and rooms of buildings, college campuses, places of work, and the like. When movement between widely separated areas is required, the wheelchair and its user are normally transported in an automobile or other vehicle thereby making the chair available for use at the destinationand at possible intermediate stops along the route. Since the space available in an automotive vehicle is quite restricted, foldable wheelchairs have been developed to facilitate storage and transport thereof. At least for the most part, such wheelchairs fold or compress transversely with the result that the height thereof is not reduced.

Ordinarily, after being folded, the wheelchair must be lifted aboard the vehicle. If the wheelchair is motorized, the vehicular loading and unloading presents a considerable problem; and in this respect, a motorized wheelchair may weigh some 150 pounds including the batteries therefor which alone may weigh 50 pounds or more. Together, the size and mass of motorized wheelchairs make handling thereof very difficult, and many prior art wheelchairs must be partially disassembled before they can be made to fit into the restricted space of a vehicle storage compartment. When partially disassembled, such prior artwheelchairs cannot be selfpropelled by their own power and, therefore, must be manually pushed or lifted into the vehicular storage space. This is difficult to do in any case and especially when it is recognized that much of the aid given to handicapped persons is by women.

In view of the foregoing, it is an object of this invention to provide an improved motorized wheelchair, and, more particularly, to provide a motorized wheelchair that can be made compact especially in the vertical dimension for storage and transport without impairing operation of the motors, controls and drive mechanism, thereby enabling the wheelchair to be propelled under its own power along a ramp or otherwise into and out of a vehicular storage space.

It is a further object of this invention to provide an improved motorized wheelchair of the character described having a control mechanism mounted on an armrest for the convenienceof one using the wheelchair so that he may steer and control the movement thereof with facility while sitting therein. Still a further object is to provide such a wheelchair with detachable armrests one of which has the control mechanism thereon, whereby a nurse or other attendant assisting the invalid may fold and compact the wheelchair, and may then use the detached control mechanism for steering and propelling the wheelchair along a ramp or the like and into (or out of) a vehicular storage space.

Additional objects and advantages of the invention, especially as concerns particular advantages andchar acteristics thereof, will become apparent as the specification continues.

DESCRIPTION OF THE DRAWINGS ofa motorized wheelchair constructed in accordance with this invention; and

FIG. 2 is a perspective view looking toward therear of the wheelchair but with the armrests removed and the backrest folded or pivoted fowardly to flatten against the seat in overlying relation therewith.

DESCRIPTION OF TI-IE PREFERRED EMBODIMENT As shown in the drawings, a wheelchair embodying the present invention comprises a seat 11 which is mounted upon a rigid frame 12 of structural members such as steel oraluminum, the latter having the advantages of lightweight, being rustproof, and capable of being-anodized in various colors. A'pair of tire-.

equipped rear drive wheels 13 are rotatably mounted on and provide rear support for the frame 12. A pair of tire-equipped front wheels are carried by the frame 12 and provide front support therefor. The front wheels 14 are in the nature of castors and are freely pivotal or swingable about generally vertical axes, as is evident in FIG. 1, respectively defined by axel structures 15.

The frong wheels 14 and supports therefor are constructed and arranged so as to trail the axels 15, I

thereby effectively being tucked under the frame 12 to reduce the overall dimensions of the chair. Both the rear and front wheels are of disc-type construction to improve the strength factor thereof and to obviate warpage, spoke damage, etc., that often characterizes other types of wheel construction.

Smooth or slick tires maybe used (although treaded tires can be employed) to minimize the tendency for dirt, mud, and other'debris to cling thereto which would then be carried thereby into the interior of houses and other building structures. Slick rear tires also significantly improve traction, especially onwet surfaces by increasing the total tire area in frictional engagement therewith. In this same reference, relatively wide tires are used, and low pressure tires (e.g., of the order of 30 psig in contrast to about 90 psig) not only tend to improve traction but also cushion the ride for an occupant of the chair, the ride otherwise being quite hard and often uncomfortable since wheelchairs are without springs.

A pair of reversible electric motors 16 are mounted on the frame 12 beneath the seat 11, and they extend longitudinally with respect thereto. Adjacent the rear ends thereof, the motors are respectively associated with gear reducers 16' rigidly attached to the motor housings and effective to reduce the output velocity of the motors and transfer a reduced velocity, increased torque to the drive wheels 13. The gear reducers 16' are transversely disposed with respect to the seat and in essentially back-to-back juxtaposition, and they are constructed and arranged to change the direction of the drive train leading from the motors by approximately 90.

The output shaft of each gear reducer 16' is equipped with a drive sprocket 17 about which is entrained an endless link or sprocket chain 18. Each chain 18 is also entrained about a second or driven sprocket l8 affixed to the associated rear wheel 13 so as to drive the same. The chain and sprocket mechanism further effects a speed reduction as between each drive sprocket 17 and rear wheel 13 associated therewith; and use of a chain drive rather than belts assures that the wheels 13 are drivingly coupled to the motors 16 with no possibility of slippage therebetween. Also, maintenance and replacement requirements are minimized by use of chain drives.

Batteries are employed as the source of motive power, and they are housed in a pair of casings or enclosures 20 and 21 carried by the frame 12 below the elevation of the seat 1 1. The batteries are rather heavy (84 pounds or more), and by providing a very low mounting therefor, the center of gravity for the wheelchair is thereby made very low which provides good stability for the chair and occupant thereof. The batteries used may take various forms, but excellent results have been obtained using two conventional 12 volt wet cell storage batteries connected in series to provide 24 volt direct current energizing potential. Use of two series-connected batteries provides the wheelchair with an extended operating range. V

The motors 16 are self-braking or equipped with a brake system that normally contrains the motors against rotation and must be positively released. By providing brakes which are normally applied or set by springs or other means, a fail-safe arrangement is included in the chair as a safety feature. Thus, if electrical power should fail due to a faulty connection, a faulty control mechanism or discharged batteries, the brakes will automatically set. To release the brakes, electric power must be applied to a pair of solenoids 22 respectively associated with the motors l6 and braking systems thereof which will exert forces in opposition to normal spring forces which are otherwise operative to set the brakes. It will be appreciated from the foregoing description that all of the working parts for propelling the wheelchair of this invention are located at levels below the seat 11.

The chair further includes a backrest 24 mounted on horizontal pivots 25 and .angularly displaceable thereabout between a normal upright position, as shown in FIG. 1 (the disposition of such upright position may be adjusted to the comfort of the occupant), and a downwardly folded flat position overlying the seat 11, as shown in FIG. 2; Aircraft type safety fasteners requiring positive depression of a plunger before the locking pin can be moved may be used to lock the backrest 24 in the various positions of adjustment thereof. A pair of armrests 26 are detachably mounted on the frame 12; and in this respect each arm is attached to a generally vertical post 27 and is diagonally reinforced by a brace 28. The post 27 is telescopically insertable into a hollow vertically extending socket member 29 welded or otherwise rigidly attached to the frame 12, and it is selectively removabletherefrom. A series of vertically spaced holes or apertures in. each socket member 29 are adapted to selectively receive a pin 32 which thereby provides adjustable settings for holding each post 27 and the armrests 26 at a desired height.

As shown in FIG. 1, the backrest 24 and the armrests 26 provide a superstructure extending above the seat 11 of thewheelchair in their normal positions of use. The armrests 26 can be easily detached and removed from the frame 12 by raising them upwardly to withdraw them from the sockets 29, as shown by the broken line positions in FIG. 1. Vertical adjustability of the armrest 26 is shown in FIG. 1 by the lower broken line position of the right armrest, and it is accomplished by changing the location of the pins 32 upon which the posts 27 are supported within the socket members 29.

A control box 36 housing electrical controls is coupled to the drive motors 16 and to the solenoid brake releases 22 by an electrical cable 37. The control box or control mechanism 36 may be mounted on one of the armrests 26 (usually the righthand side) by means such as screws or bolts 38. When the armrests 26 are in their normal positions of use as shown in FIG. 1, an occupant of the wheelchair may cause the chair to move forwardly, rearwardly, or turn to the left or right by movement of a single electrical control lever or element 39 extending upwardly from the control box sim ply by displacing the lever in the desired direction, the speed of movement of the chair being determined by the extent of the lever displacement.

- When the wheelchair is prepared to be loaded into a vehicle, the backrest 24 is folded or pivoted forwardly into a flat horizontal position overlying the seat 11, as shown in FIG. 2, and the armrests 26 are removed from their respective sockets 29 and placed on top of the backrest. The wheelchair will then have the configuration shown in FIG. 2, and will be essentially stripped of its superstructure. However, the batteries 20 and 21, the motors 16, and solenoid brake release mechanisms 22, and the chain drives will all be'intact and functionable. A nurse or other attendant may hold the control mechanism 36 and associated armrest 26 which will be independent of the wheelchair but for the connection therewith of the electrical cable 37. By operation of the electrical control lever 39 in the now hand-held control box 36, the attendant can move and control the wheelchair in its usual manner even though the wheelchairis in a folded or compacted condition with no superstructure.

The wheelchair can thereby be self-propelled up a ramp or the like into the interior of a van, trunk of a car, or other storage space in a vehicle. Since the wheelchair is entirely self-propelled, it may be stowed away in a vehicle by a woman or other person assisting I the invalid and not physically able to lift and otherwise manipulate a very heavy and relatively bulky chair. Because the wheelchair in this condition is without superstructure, it may be stored in a vehicle or other place having a low vertical clearance. The wheelchair may similarly be unloaded from the vehicle, as by backing it out, again by using its own self-control motive power. Accordingly, it will be appreciated that the motorized wheelchair of this invention may be loaded and unloaded from vehicles and may beotherwise maneu- The wheelchair may be provided with the usual footrests 41 comprising rigid metal plates having heel abutments extending upwardly therefrom that may be flexible bands anchored at the ends thereof to upright posts. The footrests 41 are carried at the lower end portions of tubes or shafts 42 which telescope into hollow sockets 43 fixedly secured to the frame 12. Thefootrests 41 may be pivoted into generally vertical orientations to facilitate access to the seat 11, and they may be adjusted to accommodate the requirements of the individual using the chair. As respects the present invention, the footrests 41 and components associated therewith may all be conventional both in terms of structure and function.

When one wishes to enter and leave the wheelchair, the right-hand armrest 26 may be withdrawn from the socket 29 and displaced 180 so as to locate the control box 36 along the outside of the armrest which may then be replaced in the socket. Such reversal in orientation of the armrest is depicted in FIG. 1 by broken lines. Locating the control box 36 along the outside of the armrest 26 evidently leaves the areas above the seat 1 1 unobstructed, thereby facilitating the movement of an individual into and out of the chair. In use of the chair, however, the control box 36 is located so as to project inwardly, as shown in FIG. 1, which is advantageous because it reduces the transverse dimension of the chair and protects the control box' from being damaged by abutment with door frames and other obstructions through which and along which the wheelchair must move.

The control mechanism itself may be of a commercial variety, and one found to be very satisfactory is known as a proportional progressive transistorized control system. The control lever 39 thereof has a universal motion, and the chair moves forwardly and rearwardly by respectively displacing the control element forwardly and rearwardly, the chair turns rapidly to the left and to the right, respectively, by displacing the control lever to the left and to the right, and any combination of mixed forward and lateral travel can be provided for the chair simply by displacing the universally movable control lever 39 in the direction that movement of the chair is desired. It will be apparent that two separate drive trains are incorporated in the chair, one for each of the rear wheels 13. Accordingly, one or the other or both of the drive chains are selectively energized depending upon the directional displacement given to the control lever 39.

As previously stated, whenever the control lever 39 is in the neutral position and whenever there is a power failure of any type, the braking mechanisms are automatically energized to constrain the wheelchair against movement. As a further safety measure, an additional on-off switch 44 may be included in the control mechanism 36, and in the off position thereof it disconnects the control mechanism so that manipulation of the lever 39 will not energize the wheelchair. The switch 44 is preferably placed in the off position thereof whenever the chair is not being actively moved, thereby preventing movement of the chair by accidental or unintentional movement of the control lever 39. Further, an additional on-ofi' switch 45 may be incorporated in the control element, and it functions to interrupt the circuit of the control lever 39 to the solenoids 22, thereby permitting. the braking mechanism to remain actuated sition thereof. This is advantageous-in that it permits the drive trains to be energized with the brakes actuated and enables an occupant of the chair to move the same carefully and slowly over a curbing or similar obstruction having a crest which might result in loss of control of the chair after it passes over the highest point thereof were it not for the braking system being actuated.

As previously indicated, the batteries used may be serially connected l2 volt batteries in which case the motors 16 and other electrical components, such as the solenoids 22, will be 24 volt direct current devices. The motors 16 may be /3 horsepower permanent magnet motors, and the gear reducers 16' may be selected to provide a gear reduction resulting in optimum speed and torque delivery to wheels 13. As a specific example, the gear reduction may be in the ratio of 5 to l which will permit the chair to be driven at a velocity of about 5 miles per hour carrying a 175 pound occupant and to climb a grade of approximately 20. Different ratios may be provided to suit any particular environmental requirements.

While in the foregoing specificationan embodiment of the invention has been set forth in considerable detail for purposes of making a complete disclosure thereof, it will be apparent to those skilled in the art when the control lever is displaced from the neutral pothat numerous changes may be made in such details without departing from the spirit and principles of the invention.

What is claimed is:

1. A motorized wheelchair comprising: frame structure; 'a seat supported by said frame; a backrest supported by said frame for movement between an upright position of use and a generally horizontal position minimizing height of said wheelchair for storage and transport; a pair of armrests movable with respect to said frame between an upright orientation of use in which they are carried by said frame on each side of said seat and a height-minimizing position for storage and transport; a pair of drive wheels rotatably mounted on said frame; a pair of self-braking motors mounted on said frame and drivingly coupled to said drive wheels; and a motor control unit movable between a position of patient use in which it is carried by one of said armrests in the upright position of use thereof and a storage and transport position and being operable to control and steer said wheelchair both when said armrests and said backrest are in upright positions and when said armrests and said backrest are disposed for storage and transport, thereby enabling said wheelchair to be loaded into and removed from a vehicle under its own power by an attendant holding and manipulating said motor control unit; said motor control unit being mounted along one side of the armrest carrying the same when in its upright orientation of use so as to lie withinthe transverse dimensional limits of said armrests when said wheelchair is in motion, and the armrest equipped with said control unit being reversibly I positionable from front to rear in upright orientation on such one sideof said seat so that said control unit will lie outwardly beyond the transverse dimensional limits of the associated armrest to leave said seat obstructed to facilitate access thereto.

2. The motorized wheelchair of.claim l in which said backrest is pivotally supported by said frame for angular displacements between the aforementioned upright position and generally horizontal position, said backrest in the'latter position thereof being disposed in overlying relation with said seat. w

3. A motorized wheelchair comprising: frame structure; a seat supported by said frame; a backrest supported by said frame for movement between an upright position of use and a generally horizontal position minimizing height of said wheelchair for storage and transport; a pair of armrests movable with respect to said frame between an upright orientation of use in which they are carried by said frame on each side of said seat and a height-minimizing position for storage and transport; a pair of drive wheels rotatably mounted on said frame; a pair of self-braking motors mountedvon said frame and d'rivingly coupled to said drive wheels; a motor control unit movable between a position of patient use in which it is carried by one of said armrestsin the upright position of use thereof and a storage and transport position and being operable to control and steer said wheelchair both when said armrests and said backrest are in upright positions and when said arm rests and said backrest are disposed for storage and transport, thereby enabling said wheelchair to be loaded into and removed from a vehicle under its own power by an attendant holding and manipulating said motor control unit; said seif-braking motors including brake mechanism operative to resist rotation of said drive wheels automatically whenever motive power to said wheelchair is interrupted; electrically energizable brake release means electrically connected with said motor control unit so as to release said brake mechanism upon manipulation of said control unit to apply motive power to said wheelchair; and a pair of switch means connected in circuit with said control unit, one such switch means being a manually operable safety switch operative in one position thereof to disable said control unit to apply motive power to said wheelchair to prevent inadvertent movement thereof, and the other such switch means being a manually operable creeper-control switch operative in one position thereof to disable said brake release means to maintain said brake mechanism in the brake applying mode thereof upon application of motive power to said wheelchair to enable the same to traverse curbs and the like.

4. The motorized wheelchair of claim 3 in which said motor control unit is mounted along one side of the armrest-carrying the same when in its upright orientation of use so as to lie within the transverse dimensional limits of said armrests when said wheelchair is in motion, in which the armrest equipped with said control unit is reversibly positionable from front to rear in upright orientation on such one side of said seat so that said control unit will lie outwardly beyond the transverse dimensional limits of the associated armrest to leave said seat unobstructed to facilitate access thereto, and in which said backrest is pivotally supported by said frame for angular displacements between the aforementioned upright position and generally horizontal position, said backrest in the latter position thereof being disposed in overlying'relationwith said seat. 

1. A motorized wheelchair comprising: frame structure; a seat supported by said frame; a backrest supported by said frame for movement between an upright position of use and a generally horizontal position minimizing height of said wheelchair for storage and transport; a pair of armrests movable with respect to said frame between an upright orientation of use in which they are carried by said frame on each side of said seat and a heightminimizing position for storage and transport; a pair of drive wheels rotatably mounted on said frame; a pair of self-braking motors mounted on said frame and drivingly coupled to said drive wheels; and a motor control unit movable between a position of patient use in which it is carried by one of said armrests in the upright position of use thereof and a storage and transport position and being operable to control and steer said wheelchair both when said armrests and said backrest are in upright positions and when said armrests and said backrest are disposed for storage and transport, thereby enabling said wheelchair to be loaded into and removed from a vehicle under its own power by an attendant holding and manipulating said motor control unit; said motor control unit being mounted along one side of the armrest carrying the same when in its upright orientation of use so as to lie within the transverse dimensional limits of said armrests when said wheelchair is in motion, and the armrest equipped with said control unit being reversibly positionable from front to rear in upright orientation on such one side of said seat so that said control unit will lie outwardly beyond the transverse dimensional limits of the associated armrest to leave said seat obstructed to facilitate access thereto.
 2. The motorized wheelchair of claim 1 in which said backrest is pivotally supported by said frame for angular displacements between the aforementioned upright position and generally horizontal position, said backrest in the latter position thereof being disposed in overlying relation with said seat.
 3. A motorized wheelchair comprising: frame structure; a seat supported by said frame; a backrest supported by said frame for movement between an upright position of use and a generally horizontal position minimizing height of said wheelchair for storage and transport; a pair of armrests movable with respect to said frame between an upright orientation of use in which they are carried by said frame on each side of said seat and a height-minimizing position for storage and transport; a pair of drive wheels rotatably mounted on said frame; a pair of self-braking motors mounted on said frame and drivingly coupled to said drive wheels; a motor control unit movable between a position of patient use in which it is carried by one of said armrests in the upright position of use thereof and a storage and transport position and being operable to control and steer said wheelchair both when said armrests and said backrest are in upright positions and when said armrests and said backrest are disposed for storage and transport, thereby enabling said wheelchair to be loaded into and removed from a vehicle under its own power by an attendant holding and manipulating said motor control unit; said self-braking motors including brake mechanism operative to resist rotation of said drive wheels automatically whenever motive power to said wheelchair is interrupted; electrically energizable brake release means electrically connected with said motor control unit so as to release said brake mechanism upon manipulation of said control unit to apply motive power to said wheelchair; and a pair of switch means connected in circuit with said control unit, one such switch means being a manually operable safety switch operative in one position thereof to disable said control unit to apply motive power to said wheelchair to prevent inadvertent movement thereof, and the other such switch means being a manually operable creeper-control switch operative in one position thereof to disable said brake release means to maintain said brake mechanism in the brake applying mode thereof upon application of motive power to said wheelchair to enable the same to traverse curbs and the like.
 4. The motorized wheelchair of claim 3 in which said motor control unit is mounted along one side of the armrest carrying the same when in its upright orientation of use so as to lie within the transverse dimensional limits of said armrests when said wheelchair is in motion, in which the armrest equipped with said control unit is reversibly positionable from front to rear in upright orientation on such one side of said seat so that said control unit will lie outwardly beyond the transverse dimensional limits of the associated armrest to leave said seat unobstructed to facilitate access thereto, and in which said backrest is pivotally supported by said frame for angular displacements between the aforementioned upright position and generally horizontal position, said backrest in the latter position thereof being disposed in overlying relation with said seat. 